Slip Clutches - Spring time prep

[DAP]

Since I'm on the road on biz ... and cannot cozy up to my Landpride rotary cutter Manual, thought I'd ask the brain trust ...

The manual I recall shows some really bad directions on how to make sure your slip clutch on your rotary cutter should be checked by drawing a pencil line across the slip clutches, turning the shaft, and making sure the plates are all moving freely.

Has anyone actually done this? What was he process?

 

[Highbeam]

Ugh. I just did the adjustment. Mine is a Rankin cutter but the slip clutch is aftermarket, yellow, and seems very common. These directions are from the mower manual.

Loosen the bolts until the clutch springs spin and then snug them up until the springs don't quite spin by hand.

Engage the PTO at idle and then stall the implement so that the clutch sits there slipping. Pretty soon it will start to smoke. Remember that smell, it's important. Stop the PTO. The smoke step is needed when new and if the implement has been setting outside long enough to be suspected of being frozen with rust.

Now tighten the springs down a half turn each. Go and use the implement at full power and keep checking for slippage via heat of the clutch pack or smoke. Tighten in 1/4 turn increments until no slippage is detected under normal conditions. Even mark the pressure plate and clutch disc to see that it is not moving under normal conditions. You want it loose enough to allow slippage under abnormal impact conditions but tight enough not to slip otherwise. You bet, there is some grey area here, the implement can still lug down the engine but it is the impacts that you want to prevent from passing into the tractor.

When I bought the mower new I assumed it was already set and mowed heavily for 10s and 10s of hours before I thought I should go through the burning in procedure. My springs are way looser, noted by the amount of threads left on the adjustment bolts, than before. I am pretty confident that my slip clutch was clamped solid and offering no protection.

 

[DK35vince]

I slip my slip clutchs (brush cutter and tiller) every spring before use, only takes me a few minutes.
I have my clutchs set very close to where I want them. So I back off the nuts on the clutch (counting the # of turns) till loose.
Jamb the tiller or cutter into the ground or heavy grass, slip the clutchs, tighten slip clutch nuts same # of turns as I loosened them. Tiller or cutter slip clutchs are ready to use.

 

[westbrooklawn]

I bought a new First Choice 56" tiller, and my owners manual didn't really have any advice on how to set the slip clutch. I assumed it had been set correctly. While trying out the tiller, I hit some football size rocks, and after the racket died down I realized the slip clutch wasn't working... luckily I didn't do any damage to my pto.

To make a long story short, it is also important on NEW equipment to make an adjustment on the slip clutch to make sure it is protecting your tractor as it should.

 

[Highbeam]

The new slip clutches do NOT come presmoked or adjusted. Mine was delivered with several turns of the adjuster nuts too tight.

 

[lynxpilot]

I wondered about the initial adjustment, much less spring time adjustment. I took the engineer approach and found some interesting things. I did calculations for my tiller, and justifiably so, since I had the gears strip in the pumpkin of the original (which according to folks here is built like a brick you-know-what) under a relatively light load, or so I thought.

The tiller says something to the effect of tractor PTO HP rating should be 35-45. So I take 45 HP and convert to ft-lb/sec, then using 540 PTO rpm, I find that the torque is something like 2500 ft-lb, given all other conditions. I don't know who makes a torque wrench that reads that high and I don't have a cheater bar long enough to apply the pressure.

I'm very reluctant to just wing it and tighten it until it doesn't slip because I like my PTO on the tractor just the way it is, with all of its teeth and all. I also don't want the slip too loose, because on a bigger field, I may not be watching for the smoke cloud out of the slip every second. And once it smokes, you probably shouldn't do anything to it for a while until it cools down, because expansion and contraction along with the friction properties of the clutch will certainly change as it cools.

Anyway, the engineer approach got me nowhere. Guess I'll just have to adust the spring loaded nuts a turn or so past slipping under a whatever load.

 

[Highbeam]

"I'm very reluctant to just wing it and tighten it until it doesn't slip because I like my PTO on the tractor just the way it is, with all of its teeth and all. I also don't want the slip too loose, because on a bigger field, I may not be watching for the smoke cloud out of the slip every second."

That's the thing. Once it is set then you shouldn't need to worry about it anymore. While getting the setting figured out it would be wise to check frequently for heat or smoke. The smell of the smoke is pretty distinct but the smoke isn't as visible as a cloud. There should be a pretty wide range of acceptable settings on that clutch. Too loose and it will just wear out sooner so ehr towards loose and snug up little bits at a time until it stays cool. Then forget about it.

 

[DAP]

Well, the Landpride manual calls for loosening the spring loaded nuts 2 full revolutions, running the PTO for 2-3 minutes. Stopping full, running it again for 2 - 3 minutes ... stopping and examining for the proper slippage (the disk mark is interrupted at all points).

I would loath having to dismantle that assembly in its entirety. You should see how Landpride has bolted on the Spline housing awning ... need a wrench with 3 or 4 bends in it to get it off through the removal access hatch!!!!!!